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United States Patent | 5,748,019 |
Wong ,   et al. | May 5, 1998 |
A circuit for producing a buffered output includes a power source, a ground, a circuit input, a circuit output, a voltage reference source, a current control pre-driver and an output driver. The circuit input receives an input signal. The circuit output produces an output signal. The voltage reference source generates a reference voltage. The current control pre-driver includes a first current source, a second current source, and control logic. The first current source is connected to the power source and has a first control input. The second current source is connected to the ground and has a second control input. The control logic is connected to the circuit input, to the voltage reference source, to the first control input of the first current source and to the second control input of the second current source. In response to a first voltage value of the input signal on the circuit input, the control logic turns off the second current source and turns on the first current source. The first current source is turned on by connecting the reference voltage to the first control input of the first current source. In response to a second voltage value of the input signal on the circuit input, the control logic turns off the first current source and turns on the second current source. The second current source is turned on by connecting the reference voltage to the second control input of the second current source. The output driver includes driver circuitry and a feedback capacitance. The driver circuitry is connected to the circuit output. The feedback capacitance includes a first end and a second end. The first end is connected to the first current source and to the second current source. The second end is connected to the circuit output.
Inventors: | Wong; Belle (San Jose, CA); Lee; Donald (San Jose, CA); Mattos; Derwin (San Jose, CA) |
Assignee: | VLSI Technology, Inc. (San Jose, CA) |
Appl. No.: | 856973 |
Filed: | May 15, 1997 |
Current U.S. Class: | 327/170; 326/83; 327/112; 327/333; 327/437 |
Intern'l Class: | H03K 005/12 |
Field of Search: | 327/108,112,170,333,362,363,378,389-391,427,434,436,437 326/82,83,86,87,88 |
4542310 | Sep., 1985 | Ellis et al. | 327/112. |
5051625 | Sep., 1991 | Ikeda et al. | 326/86. |